A discontinuous autoinhibitory module masks the A1 domain of von Willebrand factor

Autor: Pete Lollar, Yingchun Wang, Samuel A. Druzak, Renhao Li, Anum K. Syed, John F. Healey, Wei Deng
Rok vydání: 2017
Předmět:
0301 basic medicine
Von Willebrand factor type C domain
Blood Platelets
Models
Molecular
Protein Conformation
alpha-Helical
congenital
hereditary
and neonatal diseases and abnormalities
Von Willebrand factor type A domain
030204 cardiovascular system & hematology
Binding
Competitive
Article
law.invention
03 medical and health sciences
chemistry.chemical_compound
Structure-Activity Relationship
0302 clinical medicine
Von Willebrand factor
law
hemic and lymphatic diseases
von Willebrand Factor
Baby hamster kidney cell
Von Willebrand disease
medicine
Humans
Platelet
Protein Interaction Domains and Motifs
Ristocetin
biology
Chemistry
Deuterium Exchange Measurement
Hematology
medicine.disease
Peptide Fragments
Cell biology
030104 developmental biology
Platelet Glycoprotein GPIb-IX Complex
Immunology
Mutation
biology.protein
Recombinant DNA
Protein Conformation
beta-Strand
circulatory and respiratory physiology
Protein Binding
Zdroj: Journal of thrombosis and haemostasis : JTH. 15(9)
ISSN: 1538-7836
Popis: Essentials The mechanism for the auto-inhibition of von Willebrand factor (VWF) remains unclear. Hydrogen exchange of two VWF A1 fragments with disparate activities was measured and compared. Discontinuous residues flanking A1 form a structural module that blocks A1 binding to the platelet. Our results suggest a potentially unified model of VWF activation. Click to hear an ISTH Academy presentation on the domain architecture of VWF and activation by elongational flow by Dr Springer SUMMARY: Background How von Willebrand factor (VWF) senses and responds to shear flow remains unclear. In the absence of shear flow, VWF or its fragments can be induced to bind spontaneously to platelet GPIbα. Objectives To elucidate the auto-inhibition mechanism of VWF. Methods Hydrogen-deuterium exchange (HDX) of two recombinant VWF fragments expressed from baby hamster kidney cells were measured and compared. Results The shortA1 protein contains VWF residues 1261-1472 and binds GPIbα with a significantly higher affinity than the longA1 protein that contains VWF residues 1238-1472. Both proteins contain the VWF A1 domain (residues 1272-1458). Many residues in longA1, particularly those in the N- and C-terminal sequences flanking the A1 domain, and in helix α1, loops α1β2 and β3α2, demonstrated markedly reduced HDX compared with their counterparts in shortA1. The HDX-protected region in longA1 overlaps with the GPIbα-binding interface and is clustered with type 2B von Willebrand disease (VWD) mutations. Additional comparison with the HDX of denatured longA1 and ristocetin-bound longA1 indicates the N- and C-terminal sequences flanking the A1 domain form cooperatively an integrated autoinhibitory module (AIM) that interacts with the HDX-protected region. Binding of ristocetin to the C-terminal part of the AIM desorbs the AIM from A1 and enables longA1 binding to GPIbα. Conclusion The discontinuous AIM binds the A1 domain and prevents it from binding to GPIbα, which has significant implications for the pathogenesis of type 2B VWD and the shear-induced activation of VWF activity.
Databáze: OpenAIRE
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